Over the last couple of days I have been helping a mate set up a 3Phase motor on a 240V single to 240V 3phase VFD.
The motor is on a very fancy Italian industrial strength coffee grinder - it uses a 4 pole motor and a reduction gearbox to generate 425 RPM

The motor was connected as a Y and needed to be converted to ∆ so we opened up the motor and found the common point easily enough.

The common point wires were coloured red (R), white (w) and black (B)

We disconnected the common point and then looked for the other ends to wire them together to make the ∆.

Back at the terminal block there were also 3 wires (RWB) so we though that same colored pair would signify a coil for each phase but when we checked the resistance it turned out the coils had different coloured wires at each end.

ie R and W made one coil, B - R another and W - B the third.
Then it made sense, if the same coloured wires were joined that would made the ∆! connection and then additional wires were needed to connect the connections back to the terminal box

Connected it all up checked the continuity and it's running like a bought one.

I don't know if this is normally the way its done but when I thought about it, Italian motor factory, has to cope with lowest common denominator workers.
Want to make Y - join one of each colour together
Want to make ∆ - join the same coloured wires together.